Fred Ettish wrote: > I was given this problem and and having some difficulty understanding > part of it. > > The problem involves a .250 hitter who gets 5 at bats per game and > the question is ( I think) "What is the expected streak of games > where the batter gets a hit?" > > So > > The probability of not getting a hit at bat is .750. The probability > of no hits at 4 at bats is .750^5 = .237 The probability of at least > one hit per game is 1 - .237 = .763
You are in good shape up to here, if my assumption of typographical error is correct (specifically, the above should read "probability of no hits at 5 at bats") At this point, to get the expected consecutive number of games in which a batter gets a hit, you would have a geometric distribution with probability p=0.763 for each trial. Thus, expected value is 1/p = 1/0.763 = well you can figure it out from here > So the longest streak is k where .763^k=1/162 > > Can anyone explain this last step? Why set it equal to 1/162? I can't explain it. > Thanks Now, all of this also makes the assumption that the probability of getting a hit each and every at bat is the same, a dubious assumption, but perhaps a place to start. -- Paige Miller [EMAIL PROTECTED] http://www.kodak.com "It's nothing until I call it!" -- Bill Klem, NL Umpire "When you get the choice to sit it out or dance, I hope you dance" -- Lee Ann Womack . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
